Commercial cool storage design guides frequently employ stratified chamber systems that are particularly useful as a technique for shifting all or part of the electrical power requirements for generating air conditioning requirements from peak to off-peak hours. Stratified chamber systems prevent warm and cool water mixing by relying on buoyant or hydrodynamic effects rather than physical separation. Stratified chamber systems function in this manner: when cool water is introduced to a tank with warm water, a thin, naturally occurring layer of water, called a thermocline, separates the cool water from the warm water. Studies have indicated that cool water and warm water can be stored in the same vessel with a relatively thin thermocline formed therebetween if the storage and removal of the water is maintained in such a way that intermixing is reduced. It has been well established that the maintenance of a thermocline can provide effective separation of cool and warm water without the need of any type of physical separation to thereby enhance storage efficiency. Such systems are sometimes referred to as an unbaffled tank system.
For background material relating to the use and application of stratified storage systems reference may be had to a publication of Electric Power Research Institute entitled "Commercial Cool Storage Design Guide EPRI EM-3981, Project 2036-3 Final Report, May 1985". For other background material reference may be had to U.S. Pat. No. 4,315,404 which describes a cooling system for a power generating plant that employs a stratified chamber system wherein warm and cool water are received, stored and dispensed from a single vessel for use in the power plant cooling system application.
For another illustration of prior art relating to the storage of warm and cool water in a stratified system see U.S. Pat. No. 4,987,922 which issued Jan. 29, 1991. The storage tank of this system utilizes a vertical tubular column with openings at the top and bottom and with a divider plate therein separating the column into an upper portion and a lower portion with the warm water being added to or withdrawn from the tank through the column upper portion and the cool water being added to and withdrawn from the tank through the column lower portion. The apparatus in this patent, while encompassing the principle as discussed in the article entitled "Commercial Cool Storage Design Guide" as above-mentioned, has a disadvantage in that the passage of warm and cool water into and out of the vessel must take place through openings in the tubular column that are inherently of relatively small diameter compared to that of the tank and therefore higher velocities of liquid flow are encountered, thereby introducing the possibility of increased turbulence of water stored in the tank.
The present invention is concerned with an improved stratified chamber system having means for separately introducing and withdrawing warm and cool water from the interior of a vessel in a manner to reduce the possibility of turbulence and thereby minimize the possibility of intermixing the different density liquids.